PDBsum entry 3bzo

Membrane protein, protein transport

PDB id: 3bzo

Contents

Protein chains

17 a.a. *

82 a.a. *

Ligands

SO4

Waters ×86

* Residue conservation analysis

PDB id:

3bzo

Name:

Membrane protein, protein transport

Title:

Crystal structural of native escu c-terminal domain

Structure:

Escu. Chain: a. Fragment: unp residues 215-262. Engineered: yes. Escu. Chain: b. Fragment: unp residues 263-345. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 562. Strain: epec e2348/69. Gene: escu. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.50Å R-factor: 0.203 R-free: 0.225

Authors:

R.Zarivach,W.Deng,M.Vuckovic,H.B.Felise,H.V.Nguyen,S.I.Miller, B.B.Finlay,N.C.J.Strynadka

Key ref:

R.Zarivach et al. (2008). Structural analysis of the essential self-cleaving type III secretion proteins EscU and SpaS. Nature, 453, 124-127. PubMed id: 18451864 DOI: 10.1038/nature06832

Date:

18-Jan-08 Release date: 22-Apr-08

Protein chain

Q9AJ26  (Q9AJ26_ECOLX) -  EscU from Escherichia coli

Seq: 345 a.a.

Struc: 17 a.a.

Protein chain

Q9AJ26  (Q9AJ26_ECOLX) -  EscU from Escherichia coli

Seq: 345 a.a.

Struc: 82 a.a.

DOI no: 10.1038/nature06832

Nature 453:124-127 (2008)

PubMed id: 18451864

Structural analysis of the essential self-cleaving type III secretion proteins EscU and SpaS.

R.Zarivach, W.Deng, M.Vuckovic, H.B.Felise, H.V.Nguyen, S.I.Miller, B.B.Finlay, N.C.Strynadka.

ABSTRACT

During infection by Gram-negative pathogenic bacteria, the type III secretion system (T3SS) is assembled to allow for the direct transmission of bacterial virulence effectors into the host cell. The T3SS system is characterized by a series of prominent multi-component rings in the inner and outer bacterial membranes, as well as a translocation pore in the host cell membrane. These are all connected by a series of polymerized tubes that act as the direct conduit for the T3SS proteins to pass through to the host cell. During assembly of the T3SS, as well as the evolutionarily related flagellar apparatus, a post-translational cleavage event within the inner membrane proteins EscU/FlhB is required to promote a secretion-competent state. These proteins have long been proposed to act as a part of a molecular switch, which would regulate the appropriate chronological secretion of the various T3SS apparatus components during assembly and subsequently the transported virulence effectors. Here we show that a surface type II beta-turn in the Escherichia coli protein EscU undergoes auto-cleavage by a mechanism involving cyclization of a strictly conserved asparagine residue. Structural and in vivo analysis of point and deletion mutations illustrates the subtle conformational effects of auto-cleavage in modulating the molecular features of a highly conserved surface region of EscU, a potential point of interaction with other T3SS components at the inner membrane. In addition, this work provides new structural insight into the distinct conformational requirements for a large class of self-cleaving reactions involving asparagine cyclization.

Selected figure(s)

Figure 1.
Figure 1: Structure of the C-terminal domains of EscU and SpaS. a, The native cleaved CTD of EscU and SpaS with a blue arrow pointing to the auto-cleavage site. CTD is a novel / -fold with a mixed parallel and anti-parallel five-stranded twisted -sheet (topology 4, 1, 2, 3, 5) flanked by two helices on each side ( 1, 2, 3 and 4). b, Superposition of the CTD reveals a different fold for the N-terminal linker between EscU, EscU mutants and SpaS, as well as a longer C-terminal helix for SpaS.

Figure 3.
Figure 3: Auto-cleaving mechanism of EscU. a, Non-cleaved type I -bend of P263A (left), the non-cleaved type II beta bend of N262A (middle left), the non-cleaved type II beta bend of N262Di (middle right) and the native cleaved loop with a flipped His 265 (right). Note the identical conformations of the N, C, C and C at position 262 in all uncleaved forms. All maps are sigma-A weighted 2F[o] - F[c] electron density (1.5 ); water molecules are represented by the red spheres. b, Detailed mechanism for the asparagine cyclization in EscU.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2008, 453, 124-127) copyright 2008.

Figures were selected by an automated process.